Tungstosilicic acid is used in application such as coal gasification.
Prior to this invention, tungstosilicic acid was made using hydrochloric acid in the critical pH adjustment steps. This resulted in chloride contamination of the material and required an extra crystallization step in the process to remove the contaminating chloride ions. This crystallization step in turn resulted in a loss of product to the crystal mother liquor.
The process of the present invention avoids the extra crystallilzation step, the contamination problems and the economic disadvantages of losing product all of which result from use of hydrochloric acid.